Current trends in mobile computing are enabling new usage models based on local distributed system either among similar devices, such as laptops, smart phones, etc., or between a mobile device and an element in the infrastructure. However, in this growing trend, the conventional solutions for calculating device proximity between computing devices (e.g., the distance or proximity between various computing devices) are limited in their scope and/or inefficient. One solution involves Near Field Communication (NFC) that requires extremely close range (e.g., 10 cm) between devices to work. Further, this NFC solution may work for systems that integrate a small smart-phone device with a fixed point-of-sale NFC reader; however, with two or more mobile devices, such as netbooks, personal computers (PCs) in a group setting (e.g., classroom), this NFC solution does not work because it requires an exact placement of NFC contact points between the devices.
Another conventional solution is the single-antennae RSSI measurement technique. However, this technique is not suitable due to high variance signal strength measurements caused by multi-path signal propagation and other sources of interference. Yet another conventional solution is time synchronization, which is typically accomplished using over-the-network Network Time Protocol (NTP). This solution is suitable for synchronizing the system clock to user-perceptible levels over a wide area, but does not provide the tight fine-grain synchronization necessary for doing audio co-localization.